Emissions continue to pose numerous problems for the global community. Pollutants in gas streams can cause adverse human health effects and affect global climate change. To protect public health and the environment, environmental agencies around the globe regularly monitor levels of numerous pollutants. In particular, the atmospheric presence of sulfur dioxide (SO2), nitrogen dioxide (NO2), particulate matter (PM), carbon monoxide (CO), volatile organic compounds (VOC), and other toxic pollutants are monitored and evaluated to assure continued health and safety. Some of these pollutants are emitted directly or indirectly into the atmosphere from a variety of sources, including, but not limited to, power plants, factories, waste treatment plants, buses, cars, trucks, airplanes, bulldozers, and commercial and industrial processes. Principally, emissions of carbon dioxide (CO2) from coal-fired power plants create various environmental problems that countries, like the United States, are attempting to obviate due to global warming concerns and continued dependence on coal-fired power plants as energy sources.
Coal-fired power plants and other facilities producing electrical power or steam conventionally burn hydrocarbons in a process that produces substantial emissions of greenhouse gases, particulates, and other toxic air pollutants. In conventional systems, power plant emissions are unavoidable, and emission control systems, devices, and methods typically require multiple, expensive, post-combustion treatment systems that capture SOx, NOx, and other toxic air pollutants. In addition, to date, economical methods for capturing and sequestering CO2 do not exist. Accordingly, power plants continue to contribute significantly to greenhouse gases. The few available methods for combustion treatment of gases reduce the fuel efficiency of power plants, by preventing complete combustion and significantly add to power plant operating costs.
Generally, known devices and methods in the prior art either remove or destroy particles of pollutants before they are emitted into the atmosphere. These devices and methods use mechanical, electrical, and chemical processing means. Examples of such devices include electrostatic precipitators, baghouses, scrubbers, and catalytic converters. While these devices are somewhat effective, each has limitations.
An electrostatic precipitator is a device that removes particles from gas streams using forces associated with induced electrostatic charges. While these devices are known to remove particulate matter, e.g. dust and smoke from gas streams, they generally do not work well in removing carbon particles, such as, for example, carbon particles, resulting from the burning of diesel fuel.
Baghouses are devices used to collect particulates and are generally effective in collecting carbon and fly ash particulates. These devices, however, are prone to moisture, particularly when used in small power plant applications. Excessive moisture can cause the particles to cake within baghouses, preventing proper operation.
Scrubbers are devices that collect particulates and gases. Scrubbers are classified into wet and dry scrubbers. Wet scrubbers either dissolve or absorb particulates using liquids. Polluted particles and gas streams are brought in contact with a scrubbing liquid, e.g. by spraying, such that pollutants are removed. The dissolved pollutants and resulting waste water, however, can form corrosive solutions which thereafter have to be disposed of according to regulatory standards. Dry scrubbers, in contrast, do not saturate gas streams. These devices add absorbent alkaline materials to pollutant gas streams. The alkaline materials react with the gas stream to form a solid byproduct. Both types of scrubbers must be designed considering the properties of the pollution. As a result, scrubbers which are designed to remove SOx from pollutant-filled gas streams are typically not as effective at reducing NOx from pollutant-filled gases.
Catalytic converters are devices incorporated into an automobile's exhaust system. These devices reduce the amount of pollutants found in exhaust gases to environmentally harmless levels. A catalytic converter may be placed anywhere in the exhaust system. For optimum efficiency, however, it is necessary to locate a catalytic converter as close as possible to the combustion chamber in an engine compartment. As such, these devices have several limitations.
A pollution control device is also described in U.S. Pat. No. 5,366,701, the disclosure of which is incorporated by reference in its entirety. This device relates to the ionization of a gas stream from a source by passing gas streams through a resonance field. In addition, potentialization and disassociation of molecules that make up the gas stream occurs by passing the stream through a continuous electrical arc. While a significant improvement over the prior art devices described thus far, in practice, this device produces a treated gas released in an excited state at an elevated temperature, such that post-processing of the treated gas is still required.
Due to the limitations described and others known in the art, the pollution control industry is still in need of apparatuses and methods that overcome these and other limitations. In particular, there is still a need for apparatuses, and methods that do not create hazardous pollutant byproducts. There is also a need for cost-effective apparatuses, and methods that do not consume high amounts of energy. There is a further need for apparatuses adaptable for retro-fit with existing sources of pollution, particularly those sources that emit gas streams from combustion processes.
While certain aspects of prior art pollution control devices have been discussed, technical aspects of these devices are in no way disclaimed and it is contemplated that the claimed invention may encompass one or more technical aspects of the prior art devices discussed herein.